Thermodynamics of beta-amyloid fibril formation

Amyloid fibers are aggregates of proteins. They are built out of a peptide called $\beta$--amyloid (A$\beta$) containing between 41 and 43 residues, produced by the action of an enzyme which cleaves a much larger protein known as the Amyloid Precursor Protein (APP). X-ray diffraction experiments have shown that these fibrils are rich in $\beta$--structures, whereas the shape of the peptide displays an $\alpha$--helix structure within the APP in its biologically active conformation. A realistic model of fibril formation is developed based on the seventeen residues A$\beta$12--28 amyloid peptide, which has been shown to form fibrils structurally similar to those of the whole A$\beta$ peptide. With the help of physical arguments and in keeping with experimental findings, the A$\beta$12--28 monomer is assumed to be in four possible states (i.e., native helix conformation, $\beta$--hairpin, globular low--energy state and unfolded state). Making use of these monomeric states, oligomers (dimers, tertramers and octamers) were constructed. With the help of short, detailed Molecular Dynamics (MD) calculations of the three monomers and of a variety of oligomers, energies for these structures were obtained. Making use of these results within the framework of a simple yet realistic model to describe the entropic terms associated with the variety of amyloid conformations, a phase diagram can be calculated of the whole many--body system, leading to a thermodynamical picture in overall agreement with the experimental findings. In particular, the existence of micellar metastable states seem to be a key issue to determine the thermodynamical properties of the system

Hybrid Focal Stereo Networks for Pattern Analysis in Homogeneous Scenes

In this paper we address the problem of multiple camera calibration in the presence of a homogeneous scene, and without the possibility of employing calibration object based methods. The proposed solution exploits salient features present in a larger field of view, but instead of employing active vision we replace the cameras with stereo rigs featuring a long focal analysis camera, as well as a short focal registration camera. Thus, we are able to propose an accurate solution which does not require intrinsic variation models as in the case of zooming cameras. Moreover, the availability of the two views simultaneously in each rig allows for pose re-estimation between rigs as often as necessary. The algorithm has been successfully validated in an indoor setting, as well as on a difficult scene featuring a highly dense pilgrim crowd in Makkah.Comment: 13 pages, 6 figures, submitted to Machine Vision and Application

Intensive care in labour: a preliminary appraisal

This is a preliminary investigation into the value, function and practicability of an intensive care labour unit for highrisk cases. All the equipment necessary can be mounted on two standard theatre trolleys which can be moved to the patient's bedside, but there is no place at present for this equipment outside a teaching unit. The investigation reports on continuous foetal heart monitoring of 36 patients and simultaneous foetal scalp pH estimations on 16 of them. A high proportion of babies with low Apgar scores showed one of two (or both) characteristic foetal heart patterns during labour: (a) the well-known type 2 dip, (b) a steppe pattern not previously described as such. The latter is of importance because it is impossible to detect using only clinical methods.There was poor correlation between foetal pH values and Apgar rating, and between foetal pH values and monitor patterns. Moreover, the pH values of foetal scalp blood and foetal umbilical arterial and venous blood samples bore varying relations to one another. However, for practical purposes, a foetal scalp blood of pH less than 7·20 when associated with a maternofoetal pH difference of 0·250 or more should be regarded with anxiety. The place and value of intensive care are discussed

Rapid Integration Of WiFi Hotspots With A Cloud-based AAA Service

Public WiFi is typically provided by a network of smaller (local-area), independent service providers internetworked by a larger (wide-area) service provider. Currently, integration between the local-area and the wide-area service providers is a tedious process. This disclosure describes a set of vendor-agnostic application program interfaces (APIs) that enable a WiFi hotspot provider to integrate its control plane with a cloud-based authentication, authorization, and accounting (AAA) service in a self-service manner, without the direct involvement of personnel from the cloud service. This set of APIs enable a WiFi provider to self-register and self-configure its WiFi devices, such as controllers, with the cloud-based AAA service. Once registered and configured, the WiFi device can send requests to the cloud-based AAA service for creating WiFi sessions to control and account for users’ network access

Intensive care in labour: A preliminary appraisal

This is a preliminary investigation into the value, function and practicability of an intensive care labour unit for highrisk cases. All the equipment necessary can be mounted on two standard theatre trolleys which can be moved to the patient's bedside, but there is no place at present for this equipment outside a teaching unit. The investigation reports on continuous foetal heart monitoring of 36 patients and simultaneous foetal scalp pH estimations on 16 of them. A high proportion of babies with low Apgar scores showed one of two (or both) characteristic foetal heart patterns during labour: (a) the well-known type 2 dip, (b) a steppe pattern not previously described as such. The latter is of importance because it is impossible to detect using only clinical methods. There was poor correlation between foetal pH values and Apgar rating, and between foetal pH values and monitor patterns. Moreover, the pH values of foetal scalp blood and foetal umbilical arterial and venous blood samples bore varying relations to one another. However, for practical purposes, a foetal scalp blood of pH less than 7·20 when associated with a maternofoetal pH difference of 0·250 or more should be regarded with anxiety. The place and value of intensive care are discussed

Gate-to-Gate Life-Cycle Inventory of Softwood Lumber Production

To perform a life-cycle analysis, a life-cycle inventory is needed. Data from surveys of manufacturers are presented for the energy and materials required to produce 1.623 m3 (1 mbf) of planed, dry, dimension lumber from logs in the western and southern U.S. In the West and South, 53 and 41% of the log volume (3.05 and 3.92 m3) leaves the mill as planed, dry dimension lumber, respectively. A much greater portion of the energy used for production in the South is produced on site from wood fuels. CO2 emissions were greater in the South because of the wood fuel, 574 kg versus 419 kg per 1.623 m3 produced

Self-Calibration of Cameras with Euclidean Image Plane in Case of Two Views and Known Relative Rotation Angle

The internal calibration of a pinhole camera is given by five parameters that are combined into an upper-triangular $3\times 3$ calibration matrix. If the skew parameter is zero and the aspect ratio is equal to one, then the camera is said to have Euclidean image plane. In this paper, we propose a non-iterative self-calibration algorithm for a camera with Euclidean image plane in case the remaining three internal parameters --- the focal length and the principal point coordinates --- are fixed but unknown. The algorithm requires a set of $N \geq 7$ point correspondences in two views and also the measured relative rotation angle between the views. We show that the problem generically has six solutions (including complex ones). The algorithm has been implemented and tested both on synthetic data and on publicly available real dataset. The experiments demonstrate that the method is correct, numerically stable and robust.Comment: 13 pages, 7 eps-figure

Autocalibration with the Minimum Number of Cameras with Known Pixel Shape

In 3D reconstruction, the recovery of the calibration parameters of the cameras is paramount since it provides metric information about the observed scene, e.g., measures of angles and ratios of distances. Autocalibration enables the estimation of the camera parameters without using a calibration device, but by enforcing simple constraints on the camera parameters. In the absence of information about the internal camera parameters such as the focal length and the principal point, the knowledge of the camera pixel shape is usually the only available constraint. Given a projective reconstruction of a rigid scene, we address the problem of the autocalibration of a minimal set of cameras with known pixel shape and otherwise arbitrarily varying intrinsic and extrinsic parameters. We propose an algorithm that only requires 5 cameras (the theoretical minimum), thus halving the number of cameras required by previous algorithms based on the same constraint. To this purpose, we introduce as our basic geometric tool the six-line conic variety (SLCV), consisting in the set of planes intersecting six given lines of 3D space in points of a conic. We show that the set of solutions of the Euclidean upgrading problem for three cameras with known pixel shape can be parameterized in a computationally efficient way. This parameterization is then used to solve autocalibration from five or more cameras, reducing the three-dimensional search space to a two-dimensional one. We provide experiments with real images showing the good performance of the technique.Comment: 19 pages, 14 figures, 7 tables, J. Math. Imaging Vi

Differential protection of neuromuscular sensory and motor axons and their endings in Wld(S) mutant mice

Orthograde Wallerian degeneration normally brings about fragmentation of peripheral nerve axons and their sensory or motor endings within 24-48 h in mice. However, neuronal expression of the chimaeric, Wld(S) gene mutation extends survival of functioning axons and their distal endings for up to 3 weeks after nerve section. Here we studied the pattern and rate of degeneration of sensory axons and their annulospiral endings in deep lumbrical muscles of Wld(S) mice, and compared these with motor axons and their terminals, using neurone-specific transgenic expression of the fluorescent proteins yellow fluorescent protein (YFP) or cyan fluorescent protein (CFP) as morphological reporters. Surprisingly, sensory endings were preserved for up to 20 days, at least twice as long as the most resilient motor nerve terminals. Protection of sensory endings and axons was also much less sensitive to Wld(S) gene-copy number or age than motor axons and their endings. Protection of γ-motor axons and their terminals innervating the juxtaequatorial and polar regions of the spindles was less than sensory axons but greater than α-motor axons. The differences between sensory and motor axon protection persisted in electrically silent, organotypic nerve-explant cultures suggesting that residual axonal activity does not contribute to the sensory-motor axon differences in vivo. Quantitative, Wld(S)-specific immunostaining of dorsal root ganglion (DRG) neurones and motor neurones in homozygous Wld(S) mice suggested that the nuclei of large DRG neurones contain about 2.4 times as much Wld(S) protein as motor neurones. By contrast, nuclear fluorescence of DRG neurones in homozygotes was only 1.5 times brighter than in heterozygotes stained under identical conditions. Thus, differences in axonal or synaptic protection within the same Wld(S) mouse may most simply be explained by differences in expression level of Wld(S) protein between neurones. Mimicry of Wld(S)-induced protection may also have applications in treatment of neurotoxicity or peripheral neuropathies in which the integrity of sensory endings may be especially implicated

Advancing models of best practice in academic governance and management in higher education institutions in Kazakhstan

This is a collaborative research project of Nazarbayev University Graduate School of Education (NUGSE) in partnership with the Graduate School of Education of University of Pennsylvania (PennGSE). The Project aims at studying how academic leaders at public and private institutions in Kazakhstan are preparing for greater institutional autonomy and encouraging innovation [1]